1. Field of the Invention
The present invention relates generally to valves, and more particularly, but not by way of limitation, to a constriction valve for controlling the flow of fluids from a well, especially during uncontrolled well blowouts. The present invention more specifically relates to devices for constricting around and closing off the annular flow volume surrounding a pipe or tubing present in a well. The present invention may therefore be described as an annular blowout container (ABOC) and therefore relates to an improved constriction valve for controlling the flow of drilling fluids and hydrocarbon fluids and gases in a state of free flow known as blowout in drilling and production phases, in combination with additional valves that may be positioned at the well head.
2. Description of the Related Art
The control and containment of free flowing fluids, hydrocarbon fluids and gases in well drilling and production operations is critical. There are a wide variety of blowout preventers (BOPS) but these have a long history of failure. In particular, various types of shear rams commonly used today are hydraulically operated and are typically only designed to cut the tube section of the drill pipe being used, not to stop the flow of fluids. In addition, shear rams rely for proper placement and function on the drill pipe being in a center position of the hole to cut or sever the drill pipe tube only. Most blowouts, however, occur during the tripping phase of drilling, and as a result, other drilling tools such as drill collars and/or downhole tools are frequently within the section to be closed.
A further significant cause of failure of blowout preventers used today results from the fact that typically only the body of the BOP is tested at API recommended pressures. The internal components of BOPs used today rely on elastomeric components installed in grooves to make contact with the body of the valve. These elastomeric components will generally not contain higher pressures above 5,000 psi. Therefore, the BOPs in use today are significantly overrated for use in conjunction with higher pressures.